Despite efforts to find a cure, there are some ills within journalism that seem stubbornly resistant to eradication. A reader wrote: "the two corrections … published on Monday 2 January … showed major mistakes on numbers included in the original articles, sufficiently great to cast doubt on the whole thrust of the articles…"

The first of these corrections was: "A story said that big food retailers in Britain had permission for another 21.4m sq ft of supermarket space, enough for 'more than 16,000 new stores'. At an average of 13,000 sq ft, that should have been 1,600 new stores. A regional breakdown should have said 7.4m sq ft of such space was planned for Scotland, instead of 16.7m; 5.1m for the south-east, instead of 11.6m; and 4.8m for the north-west, instead of 10.9m (Revealed: how supermarkets plan to build thousands more stores, 22 December, page 3)."

And the second was: "Some World Bank figures were misportrayed in a story headlined Migrants flood out of Europe in search of jobs (22 December, page 24/turned from page 1). One sentence read: 'In 2010, 1.21 million people emigrated [from Greece], according to the World Bank, equalling 10.8% of the population.' This was actually the total 'stock' of Greeks said by the bank to be living overseas as of 2010, not the number leaving the country that year. Similarly, the 1.3 million people said by the article to have arrived in Greece in 2010 actually constituted the total 'stock' of immigrants said by the bank to be living in Greece as of 2010, not the number arriving that year. The piece said 4,886 physicians emigrated from Greece in 2010; the bank cited that figure for the year 2000."

The reader went on to say: "It seems to me that there is a cultural problem among Guardian reporters, that it is of no consequence if you completely misunderstand or mis-report the figures in a story. The fact that the Guardian corrects them is better than nothing, but I think major corrections of this nature should be given much more prominence – equal to the prominence of the original story. If politicians made mistakes of this order, the Guardian would make a great fuss about it … I hope that you can urge on the editor some training of reporters on basic understanding of statistics, and of the need to check and re-check them. There needs to be a cultural change across the paper."

As readers' editor, I can and do urge more training and better use of statistics. In the past year there have been three sessions with external statistical experts for journalists at the Guardian. And the small team that produces the Guardian's data blog is always ready to help journalists with knotty stats problems. So, why is the misuse of numbers still such an issue – one that perhaps goes beyond a slapdash approach which may account for some of the mistakes that are made?

I think the reader makes a good point about the need for a profound cultural change. Even before journalism became a trade dominated by graduates, practitioners were not traditionally famed for their skills with numbers or love of them – bar some specialists in the likes of business reporting. The present-day preponderance of university degree holders does not seem to have changed this much, perhaps because the majority have a background in humanities rather than sciences (I tried to check whether the Guardian held any analysis of educational backgrounds of staff; it doesn't).

At the same time there is a growing number of stories based on the interrogation and mining of statistics, not least because the world has been in the grip of a financial crisis that no longer is confined to the business pages. One non-business reporter said: "I live in constant fear of making a whopping error because I don't truly understand credit default swaps, the mechanics of a bond auction, etc…" Reporters also have to file more quickly and more often, which can lead to more errors. Subeditors – even assuming they have numerical skills – have to edit more quickly. Finally, the Guardian's success in attracting more than 60 million unique users to its website each month means that there are more readers with their fingers hovering over their buzzers.